Degradation of the dielectric and piezoelectric response of β-poly(vinylidene fluoride) after temperature annealing

Silva, Marco Aurélio Pinto; Costa, Carlos M.; Sencadas, Vítor; Paleo, A. J.; Lanceros‐Méndez, S.

doi:10.1007/s10965-010-9550-x

Cited by 68 publications

(50 citation statements)

References 33 publications

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“…Moreover, the use of higher electric fields during processing contribute to dipole alignment and consequently to electrical poling of the PVDF fibers [25] , leading to high responsive piezoelectric fibers. The quantification of the β-phase content of the electrospun samples can be performed from the FTIR spectra applying (equation 2) and following the procedure explained in [6,26] :…”

Section: Effect Of Plasma Treatment On Pvdf Fiber Morphologymentioning

confidence: 99%

“…Nevertheless, these kind of results have to be considered with care since DSC heating curves recorded at low heating rates can present more than one endotherm due to the recrystallization taking place during the scan itself after first melting and also a distribution of crystal sizes could produce the same effect. [26] The degree of crystallinity (X c ) of the samples was determined from the DSC thermograms using equation 3 [22] :…”

Section: Thermal Characterizationmentioning

confidence: 99%

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Influence of oxygen plasma treatment parameters on poly(vinylidene fluoride) electrospun fiber mats wettability

Correia

Ribeiro

Sencadas

et al. 2015

Progress in Organic Coatings

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Lanceros-Méndez, S. (2015). Influence of oxygen plasma treatment parameters on poly(vinylidene fluoride) electrospun fiber mats wettability. Progress in Organic Coatings, 85 151-158.Influence of oxygen plasma treatment parameters on poly(vinylidene fluoride) electrospun fiber mats wettability AbstractElectrospun poly(vinylidene fluoride) (PVDF) fiber mats found applications in an increasing number of areas, such as battery separators, filtration and detection membranes, due to their excellent properties. However, there are limitations due to the hydrophobic nature and low surface energy of PVDF. In this work, oxygen plasma treatment has been applied in order to modify the surface wettability of PVDF fiber mats and superhydrophilic PVDF electrospun membranes have been obtained. Further, plasma treatment does not significantly influences fiber average size (~400 ± 200 nm), morphology, electroactive B-phase content (~80-85%) or the degree of crystallinity (Xc of 42 ± 2%), allowing to maintain the excellent physic-chemical characteristics of PVDF. Plasma treatment mainly induces surface chemistry modifications, such as the introduction of oxygen and release of fluorine atoms that significantly changes polymer membrane wettability by a reduction of the contact angle of the polymer fibers and an overall decrease of the surface tension of the membranes.

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Section: Effect Of Plasma Treatment On Pvdf Fiber Morphologymentioning

confidence: 99%

Section: Thermal Characterizationmentioning

confidence: 99%

Influence of oxygen plasma treatment parameters on poly(vinylidene fluoride) electrospun fiber mats wettability

Correia

Ribeiro

Sencadas

et al. 2015

Progress in Organic Coatings

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“…While, no appreciable change in the topography and morphology of the samples was observed, the d33 value remains unchanged at ~50 pm/V, for samples stored at ambient conditions ( Figure 4c); however, upon annealing the d33 value reduces slightly to ~43 pm/V (Figure 4d), due to possible reorganisation within the crystal structure induced by the increase of molecular mobility with increase of temperature. [34] The self-polarization of the β-phase crystal in the PVDF membranes has also been verified by the piezoelectric effect based voltage generation. The mechanism for the self-alignment of the β-crystals, however, is not entirely understood as yet.…”

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confidence: 82%

Exclusive self-aligned β-phase PVDF films with abnormal piezoelectric coefficient prepared via phase inversion

et al. 2015

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Keywords: PVDF, piezoelectric effect, self-alignment, β-phase, Piezo Force Microscopy Poly(vinylidene fluoride), (PVDF), is one of the most attractive polymers owing to its remarkable pyro-, piezo-and ferro-electroactive properties. [1][2][3][4] These properties stem from its unique polymorphism which also gives rise to its extraordinary mechanical properties, high chemical resistance, good thermal stability and biocompatibility. [5] PVDF shows four significant crystalline phases α, β, δ and γ; [2,6] with the electroactive β-phase being utilized most frequently for the development of sensors, actuators [7,8] and microgenerators. [4,9,10] Owing to its importance, the formation of electroactive β crystalline phase has been intensively investigated through various routes, including melt casting, [15] solution deposition, [11] spin coating [12] and phase inversion. [13,14] While, the films or membranes formed by 2 melting/crystallisation are dominated by α-phase, [15] those obtained by spin-coating and further dried at temperature between 30-60 ºC are largely dominated by β-phase crystals. [12] For the phase inversion technique, PVDF films are formed by quenching the casting films into a nonsolvent bath to induce a series of liquid-solid and liquid-liquid phase separation events. [5,13,14] The microstructure and crystalline phase of the polymer films in phase-inversion can be controlled by adjusting paramteres like composition, [5,12] type of solvent, [16,17] quenching temperature etc. [18,19] Although PVDF films formed by this technique can have high β-phase contents, they are mostly porous and not suitable for electroactive applications. Moreover, the β-phase crystals are randomly oriented in these PVDF films and show no specific directional preference. Polarization under high electric field, [6,20] by Corona poling, [12] or by mechanical stretching [3,6,15] is subsequently carried out to obtain electroactive PVDF films. These operations need to be done at elevated temperatures (>80 o C), requiring high voltage equipment and films with dense structure and high β-phase content. Spontaneous formation of electroactive -phase in PVDF nanofibers formed by drawing was reported to have piezoelectric coefficient up to d33=58.5 pm/V. [25] Similarly, PVDF mesoscale rod arrays, without any poling process, too were also reported to possess good piezoelectric properties due to their high β content. [24] In both these cases, mechanical stretching and stress during the template guiding are believed to be responsible for the piezoelectric effect. Self-polarization of oriented β-phase crystals has also been observed in ultrathin (~20 nm) PVDF copolymer films by spin-coating or by Langmuir-Blodgett (LB) method, and is attributed to the built-in electric field, in-film stress and the strong interaction of PVDF molecules with polar water. [21,22,23] Generally speaking, PVDF films or membrane formed by melt casting, solution deposition, spin coating and phase inversion etc. do not exhibit aligned β-phase crystals without additional t...

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“…A β is the absorbance at 838 cm −1 and A β is the absorbance at 760 cm −1 . 22 The increase in the amount of β-PVDF in the composite could be due to the LSMO nanoparticles acting as additional nucleating site for the crystallization of β-phase. 23 The PVDF-LSMO composite retains its magnetic properties of the parent LSMO nanoparticles.…”

Section: Resultsmentioning

confidence: 99%

Magnetic, dielectric and magnetodielectric properties of PVDF-La0.7Sr0.3MnO3 polymer nanocomposite film

Thirmal¹,

Nayek²,

Murugavel³

et al. 2013

AIP Advances

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We have investigated the structure, magnetic and dielectric properties of PVDFLa 0.7 Sr 0.3 MnO 3 polymer nanocomposite thick film fabricated by dip coating technique along with the magnetodielectric effect. The structure and dielectric properties show the enhanced β phase in the composite compared to the PVDF film. The coupling between the ferroelectric and magnetic phases in the composite is revealed in the form of dielectric anomaly at the ferromagnetic Curie temperature. We observed 1.9% magnetodielectric effect at 300 K with the possibility of enhanced effect near the transition temperature. In addition, the analysis of the electric modulus indicates that the composite exhibits interfacial related relaxation and it follows Arrhenius Law. Our study suggests that the ac conductivity of the PVDF-La 0.

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Degradation of the dielectric and piezoelectric response of β-poly(vinylidene fluoride) after temperature annealing

Cited by 68 publications

References 33 publications

Influence of oxygen plasma treatment parameters on poly(vinylidene fluoride) electrospun fiber mats wettability

Influence of oxygen plasma treatment parameters on poly(vinylidene fluoride) electrospun fiber mats wettability

Exclusive self-aligned β-phase PVDF films with abnormal piezoelectric coefficient prepared via phase inversion

Magnetic, dielectric and magnetodielectric properties of PVDF-La0.7Sr0.3MnO3 polymer nanocomposite film

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